Mercury Monitor

ABSTRACT

An exemplary embodiment provides an analytical system for measurement of mercury concentration that can be used to monitor mercury concentration in industrial and sewage water and combustion gases.

TECHNICAL FIELD

An exemplary embodiment includes an analytical system for automaticmeasurement of mercury concentration in sample material. Exemplaryembodiments can be used to monitor mercury concentration in industrialand sewage water and combustion gases.

BACKGROUND

Measurement of mercury concentration is needed for many quality controlprocesses. Mercury is a common toxin located in many places from manysources.

A mercury analyzer known as a PA-2 Mercury Process Analyzer produced byMercury Instruments of Germany was designed for continuous measurementof the concentration of mercury in industrial sewage water used byenterprises dedicated to burning of waste, thermal power plants,treatment facilities, etc. The mercury monitor contains: a samplepreparation module where the preliminary oxidation of a sample withcorresponding reagent takes place, a reduction module where mercury isreduced to an atomic state upon addition of a reducer; a gas exchangeunit where elemental mercury is released from the liquid sample andcomes into a carrier gas, and an analytical cell where the carrier gasdelivers elemental mercury and where the amount of released mercury isdetermined via the atomic absorption method.

U.S. Pat. No. 5,679,957 discloses a device to monitor mercury emissionscontaining an input unit for a gas sample to be analyzed, a thermalatomizer where all mercury compounds dissociate to provide formation ofelemental mercury, an analytical cell capable of being heated thatconsiderably decreases the rate of oxidation of elemental mercury withdissociation products and matrix components. An atomic absorptionspectrometer measures elemental mercury.

A mercury monitor of combustion gases known as an MERCEM300Z MercuryAnalyzer produced by the firm Sick of Germany, consists of a samplingprobe, a gas line, a sample input unit, a thermal atomizer, a analyticalcell capable of being heated, a atomic absorption spectrometer and areturn pump. Combustion gas is taken with a sampling probe and istransported to the input part of the monitor. Gas passes into a thermalatomizer where all mercury, irrespective of its form, in combustion gasis transformed into elemental form, and comes to an analytical cellwhere mercury concentration is determined by an atomic absorptionspectrometer. A return pump is attached to the analytical cell exit. Thethermal atomizer and the analytical cell temperature is 1000° C.

Such prior systems contain various limitations that an exemplaryembodiment seeks to solve.

SUMMARY

Pollution in the form of material accumulation on the windows of ananalytical cell leads to considerable decrease in transparency andintensity of the probing radiation output by a atomic absorptionspectrometer through the sample material. As a result, deterioration ofanalytical characteristics and even the impossibility to carry outmeasurements may occur. Therefore, it is impossible to use thisconfiguration to determine the content of mercury in sample materialscomprising industrial waters of various enterprises such as when watercontains high percentage concentrations of chlorides and sulfates ofmetals (hardness salts). This is because evaporation and atomization ofsuch materials lead to formation of vapors of these salts whichprecipitate on the analytical cell windows. Additionally, monitors withsuch analytical cells may only have a short period of unattendedoperation, because of pollution of the analytical cell windows.Eventually because of precipitation of high concentration dissolvedsalts, the walls of the input sample unit and the thermal atomizer getblocked gas channels which makes the device unusable.

An exemplary embodiment of the mercury monitor apparatus is animprovement with improved characteristics, such as an increase inunattended operating time of an analytical cell and associated monitorsystem, and an extended functioning life of the monitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic representation of an exemplary mercury monitorsystem.

FIG. 2 shows a schematic representation of an input unit with anebulizer and a gas supply means.

FIG. 3 shows a schematic representation of the gas collector unit.

FIG. 4 shows a gas flow scheme for achieving protection of analyticalcell windows from material accumulation.

FIG. 5 shows a graph of sensitivity dependence on flow rate of a suckingout pump.

FIG. 6 shows a graphic representation of a model for spraying wateraerosol in a thermal atomizer.

FIG. 7A shows a window of the analytical cell with protective air streamafter 14 days of operation.

FIG. 7B shows a window of an analytical cell after 8 hours without aprotective air stream.

DETAILED DESCRIPTION

An exemplary embodiment of the mercury monitor includes a input sampleunit, a thermal atomizer, an analytical cell capable of being heated, agas collector unit, and a return pump. The analytical cell contains twowindows that are generally transparent windows for resonant radiation ofmercury, at least one of which is optically coupled with an atomicabsorption spectrometer. At least one gas sample inlet port serves as ainput gas port and is located in the central part of the body of theanalytical cell used in conjunction with the atomic absorptionspectrometer. The analytical cell includes at least two gas outletports, each of which is located longitudinally intermediate between theinput gas port and the corresponding adjacent window. A sample inputunit is coupled with an injecting pump capable of introducing the samplematerial to be analyzed into the thermal atomizer. The exemplaryanalytical cell has clean gas inlet flow ports or openings located inthe body adjacent its both ends. This provides a flow of sample vaporfree gas between the adjacent window and the nearest output gas port.

An exemplary embodiment provides a protective air stream between eachwindow of analytical cell and the sample gas to be analyzed, preventingdirect contact between the hot gas to be analyzed arriving in theanalytical cell and the cold surface of each window. Therefore, vaporsof highly volatile compounds present in the sample gas to be analyzedare not condensed on the windows of the analytical cell, and thetransmission coefficient of the windows for the probing radiation of theatomic absorption analyzer remains sufficiently transparent in theworking range for a long time.

An exemplary embodiment of the mercury monitor also contains anebulizer. A nebulizer holder internal wall and the nebulizer bound acavity. The cavity is connected with an internal cavity of a thermalatomizer. The holder contains a port connecting the cavity with acarrier gas supply. The nebulizer includes a spraying nozzle, a liquidinput port and a gas input port which is operatively connected bygas-liquid communication with the carrier gas supply. The carrier gassupply input port of the nebulizer is connected to a mixer with threeports; the one port is connected to the carrier gas source, the secondport is connected to a water supply, and another port of the mixer isconnected to the gas input port of the nebulizer.

A gas collector unit is operatively connected with the gas outlet portsof the analytical cell. The gas collector includes a vapor gas conduit,a gas-liquid separator and a liquid collection reservoir.

The exemplary analytical cell is optically connected with thespectrometer through a first window, and with a retroreflector through asecond window. The retroreflector is aligned such that the probingradiation beams of the spectrometer having passed through the firstwindow and through the second window, return back through the secondwindow to the sensing element of the spectrometer through the firstwindow.

Use of the nebulizer in an exemplary embodiment of the mercury monitorenables elimination of a mechanical water sample supply to the atomizer.This allows for increased reliability of the supplying device, as wellas the ability to input a sample in the form of an aerosol which reducesamount of salts precipitating on the atomizer wall. Water supplied intothe nebulizer compressed air carrier gas in the cavity provides adecreased amount of the salts precipitating directly in nozzle of thenebulizer. Use of the gas-liquid separator for treating the vapor gasafter leaving the analytical cell enables removal of water vapor fromoutput gas stream. This eliminates condensation of water in the returnpump and enables the pump to work in its regular operating mode. Use ofthe exemplary optical scheme at which radiation beams from the atomicabsorption spectrometer passing through the analytical cell comes to aretroreflector, returns into the analytical cell and then goes to aphoto detector, doubles the sensitivity of the analysis for the samelinear size of analytical cell. Additionally, the exemplary embodimentprovides compactness of spectrometer construction that increasesstability of work of the entire spectrometer.

An exemplary embodiment of the mercury monitor represented in FIG. 1,contains an injecting pump 1, a sample input 2, a thermal atomizer 3, ananalytical cell 4 with windows 5. The analytical cell includes gassample inlet port 6 and gas outlet ports 7. The monitor further includesthe gas collector 8, the return pump 9, and also the atomic absorptionspectrometer 10. The analytical cell has clean gas inlet flow portscomprising openings 11 that introduce sample vapor free gas into thecell longitudinally between windows 5 and the outlet ports 7.

An exemplary embodiment includes an injecting pump 1 is shown in FIG. 2.The nebulizer 13 is positioned in a nebulizer holder 12 in such a waythat its nozzle is directed towards an internal part of a thermalatomizer 3. The nebulizer assembly is positioned in the sample inputunit 2. The liquid port 14 of the nebulizer 13 is fluidly connected to aswitching liquid tap (not shown), which alternatively connects the port14 of the nebulizer with reservoirs containing distilled water, standardsolution, and the sample material to be analyzed. The gas port 15 of thenebulizer 13 is connected to a first port 16 of a mixer 17, whose secondport 18 is connected to a water supply 19, and its third port 20 isconnected to a carrier gas supply 21. The carrier gas supply is alsoconnected to the cavity that extends between the nebulizer 13 and itsholder 12, through the holder port 22.

In an exemplary embodiment, when determining the concentration ofmercury in combustion gases, the unit of the injecting pump 1 mayinclude a diaphragm pump that operates to supply gas to be analyzed fromthe sampling line (not shown) directly to the interior area of thethermal atomizer 3.

In an exemplary embodiment the thermal atomizer 3 can include a quartztube whose one end is hermetically fluidly connected to sample inputunit 2, and the second end is hermetically fluidly connected to the gassample inlet port 6 of the analytical cell 4. The quartz tube ispositioned coaxially with the nebulizer 13 and its holder 12, such thatthe internal diameter of the quartz tube is no less than the internaldiameter of the nebulizer holder 12. The heater controller of anexemplary arrangement operates to maintain temperature inside the quartztube in the range of 600-700° C. The entire thermal atomizer assembly isplaced into a metal protection enclosure.

The exemplary analytical cell 4 is made in the form of a cylindricalbody 44 that generally bounds an interior area 45. The body extendsalong a longitudinal direction. A gas sample inlet port 6 ishermetically welded to the middle part of the body and two framedwindows 5 are installed adjacent the opposed longitudinal body ends. Thegas outlet ports 7 are positioned longitudinally between the windows 5and the inlet port 6 on each respective side of the inlet port. In orderto form a protective air stream, the clean gas inlet flow ports oropenings 11 provide additional inlet ports through which clean gas notcontaining sample vapor in the form of air, can come into the interiorarea of the analytical cell longitudinally between the windows 5 and thegas output ports 7. This clean gas flow helps to reduce the accumulationof material on the windows. Heaters maintaining temperature of the gasto be analyzed in the range of 600-750° C. are positioned in theinterior area of the cell.

In an exemplary embodiment the gas collector 8 receives the gas from thegas outlet ports 7 of the analytical cell 4. The analytical cell outletsare operatively connected through vapor-gas conduits 23 to thegas-liquid separator 24. The separator can be in the form of a returngas cooler or refrigerator in whose external condenser jacket coolingwater flows, and the steam-gas mixture comes into its internal part. Oneend of the separator 24 is operatively connected to a liquid collectionreservoir 25 where water is collected after cooling of the vapor-gasmixture. The separator 24 is connected to a return pump 9, which in theexemplary embodiment includes a diaphragm pump.

The atomic absorption spectrometer 10 can be used as the atomicabsorption analyzer of mercury concentration utilizing the direct Zeemaneffect which is characterized by high selectivity of measurements. TheZeeman effect is described in a publication of A. A. Ganeev, et al.,herein incorporated by reference. (A. A. Ganeev, S. E. Shopulov, M. N.Slyadnev, Zeeman modulation polarization spectrometry as variance ofatomic—absorption analysis: possibilities and constraints, JAC, 1996, v.51, no. 8, p. 855-864) which is incorporated herein by reference in itsentirety.

Upon injection of water aerosol into the thermal atomizer, asrepresented in FIG. 6, part of the aerosol evaporates directly in thecarrier-gas, and a part 28 (without full evaporation of water) reachesthe heated walls of the atomizer—the quartz tube 26 placed in the heater27 which part 28 is determined by water aerosol spraying at a finiteangle 29. In order to increase the time spent by water aerosol in thecarrier gas, in the exemplary arrangement an air stream 30 isadditionally injected between the nebulizer and its holder.

Furthermore, this additional air stream 30 extends along walls of thethermal atomizer and thereby helps to retain the main stream of aerosolin an axial zone of the atomizer interior where evaporation of waterfrom an aerosol particle along with formation of salt aerosol 31 takesplace. An increase in water aerosol 32 motion trajectory leads to anincrease of evaporated water aerosol in carrier gas, and a decrease inprecipitation rate of salt 33 on the wall of the thermal atomizer. Thisresults in an increase in operating life of the unattended thermalatomizer.

During transportation of the salt aerosol inside the thermal atomizerand in the heated analytical cell (the exemplary analytical celltemperature is 650-750° C.) salt compounds partially evaporate from theaerosol particle surface and pass into carrier-gas in the form of vapor.Similarly, the salt compounds that are precipitated on the atomizersurface, when heated, partially evaporate and pass into the carrier gas.Finally, the interaction of salt particles with the surface of theheaters of the analytical cell partially evaporates such particles, andthe vapors pass into the carrier gas.

To reduce the radiation beam blocking effect from precipitation ofvapors of highly volatile compounds in sample vapor from carrier gas onthe surfaces of the windows of the analytical cell, an exemplaryembodiment of the mercury monitor was designed to have windowsmaintained in and blown with clean air, and having no direct contactbetween the cell windows with the sample containing carrier gas. Theprotection scheme for the exemplary analytical cell windows isrepresented in FIG. 4. Gas is pumped out from the analytical cellthrough the outlet ports 7 with volume speed V1=V11+V12. The gasanalyzed is supplied through the inlet port 6 with volume speed V2. Thereturn pump 9 creates negative pressure evacuation in the outlet ports 7and, in the analytical cell, the cell pressure is lower thanatmospheric, respectively. Ambient air stream flow from the inlet flowports 11 in the analytical cell is created due to evacuation in theanalytical cell. As openings 11 are located in immediate outboardlongitudinal proximity to the outlet ports, the created air streamenters openings 11 and generally immediately leaves the interior areathrough the outlet ports 7, without extending along a longitudinal axisof the analytical cell.

The volume speed of the return pump V1 is higher than volume supplyspeed of gas analyzed in the analytical cell V2, therefore, the volumespeed of protective air stream V3=V31+V32 will make the value V3=V1−V2.Dependence of measurement sensitivity on speed of the return pump V1 atconstant rate of supply of gas vapor analyzed V2=2 l/min is shown inFIG. 5. If pumping out speed is less than supply speed (0-2 l/min), thegas analyzed occupies the entire cell, including the regions between theoutlet ports 7 and cell windows 5, sensitivity being maximized (underexisting experiment conditions, sensitivity is proportional to theeffective length of the analyzed gas layer).

With an increase in pumping out speed (2-4 l/min) the gas analyzed fromthe regions between windows 5 and the outlet ports 7 are replaced withatmospheric air, and consequently the sensitivity of measurements drops.The further increase in pumping-out speed (4-9 l/min) leads tonegligible change of sensitivity, i.e. increase of pumping speed leadsonly to increase in protective air stream with only an insignificantdecrease of effective length of the layer of the gas analyzed.

The concentration of mercury in the air must be such that the air whichentered into the analytical cell (together with mercury) should noteffect results of mercury measurement in a water sample. In an exemplaryembodiment, concentration of mercury should not exceed a value of 6μg/m³ (at 1 hour stability at the level of 10%) that is virtually equalto threshold allowable concentration in working area (10 μg/m³).

The output of a pressure pump is connected to the sample input unit 2after which gas analyzed comes into the thermal atomizer 3 whosetemperature is 800-950° C.

This temperature is enough to convert fixed mercury to elemental form,and also to considerably decrease the rate of oxidation of elementalmercury. Gas from the thermal atomizer is transported in the analyticalcell 4 heated to 850-950° C., through its sample inlet port. In anexemplary embodiment, to protect the windows against precipitation ofvolatile compounds which are present in the gas being analyzed, theanalytical cell has a construction at which windows are blown with cleanair that prevents direct contact of the window with gas analyzed. In anexemplary embodiment, the gas outlet of the analytical cell is connectedto the gas collector unit in which temperature of gas that has beenanalyzed decreases to a level, which allows return pumping to beperformed. As the return pump provides a higher flow than the pressurepump delivering gas to the inlet port, it leads to creation of adifferential pressure air stream through clean gas inlet port openingsabout the inside of the windows of the analytical cell, therebyprotecting the windows from pollution.

In an exemplary embodiment, the mercury monitor enables increasing theinterval of unattended operation by at least by 40 times.

EXAMPLES

Exemplary embodiments of a mercury monitor using the principalsdescribed herein are further illustrated by the following examples,which are set forth to illustrate the presently disclosed subject matterand are not to be construed as limiting.

Example 1 Determination of Total Content of Mercury in TechnologicalWater of a Thermal Power Plant

Technological water contains a high concentration of dissolved hardnesssalts (1-5%). The water to be analyzed comes into the tank which isconnected to the input of the switching liquid tap. Other inputs of thevalve are connected to the distilled water reservoir and with standardsolution, necessary to carry out blank measurement and calibration ofthe atomic absorption spectroscopy monitor.

The output of the switching liquid tap is connected to the liquid portof the nebulizer. The source of compressed air is connected to the gasport of the nebulizer. Compressed air purified of dust and oil vapors,for example, by means of dust and an oil filter, passes through thenebulizer, creates evacuation in the region of the gas nozzle (Venturi'seffect) that leads to suction of liquid from the liquid channel of thenebulizer and coming to the gas nozzle. Slowly incoming liquid isaffected in the gas nozzle by the fast air stream that leads toformation of water aerosol which comes into the thermal atomizer.

In the exemplary thermal atomizer whose temperature is in the range of600-700° C., water evaporates from aerosol particles and all mercurycontained in them converts into atomic form at this temperature. Uponevaporation of water the small solid particles of salts (salt aerosol)are formed and are present in suspension in the air which serves ascarrier gas. Further all formed components are transported by thecarrier gas into the interior area of the analytical cell through itsgas sample inlet port.

Simultaneously, the atmospheric air comes into the analytical cellthrough clean gas inlet flow port openings, preventing direct contact ofthe gas being analyzed with the surfaces of the windows. A steam-gasmixture comes out from the gas outlet ports of the analytical cellthrough the vapor gas conduit gas tee into the liquid gas separator,made as the return gas cooler in whose external cooling jacket thecooling water flows.

The second end of the vapor gas conduit gas tee is connected with apipeline of the liquid gas separator to the liquid collection reservoirin which the water is condensed in the return cooler and is collected.The pipeline is installed in such a way that its second end in theliquid collection reservoir is always below water level (at the monitorstart up, an additional amount of water is filled in this reservoir),thus, it performs the function of a water lock for the gas part. Thesecond end of the return cooler or refrigerator is connected to thereturn pump, inducing the sucking-out of the gas stream after theanalytical cell.

Upon formation of water aerosol inside of the nebulizer, the part offormed aerosol precipitates on the internal wall of the gas nozzle. Asthe water analyzed contains a high concentration of hardness salts,evaporation of water from precipitated aerosol leads to accumulation ofsalts on internal surface of the gas nozzle that causes a change ofnozzle geometry and fast contamination of the nebulizer. In an exemplaryarrangement to eliminate contamination of the nebulizer an additionalamount of distilled water is introduced into the nebulizer cavity withcompressed air and continuously washes out the nozzle and removesprecipitated salts from it.

Example 2 Protective Air Stream Vs. Without Protective Air Stream

An exemplary embodiment of the analytical cell unit has been tested viaanalysis using a real water sample. FIG. 7A shows the windows with aprotective air stream. FIG. 7B shows the windows without the protectiveair stream. The Figures allows one to conclude that windows with theprotective air stream remain operative (probing radiation of the atomicabsorption spectrometer continues to pass through the central part ofradiation transparent windows) after 14 days. The windows without theprotective air stream reach a nonoperational state after about 8 hoursof operation.

Example 3 Determination of Mercury Content in Combustion Gases

Combustion gases have rather complex composition that may include: smokeparticles, water vapors, O₂, CO₂, NO, NO₂, SO₂, HCl, HF, Hg and itscompounds. In addition, the temperature of gas at the sampling point maybe about 100-200° C. The sampling probe is connected with the pumpingunit which is a heated injecting pump with gas lines. An exemplaryembodiment uses a diaphragm pump with Teflon coating of all elementscontacting with gas stream as the injecting pump.

Of course these embodiments are exemplary and alterations thereto arepossible by those having skill in the relevant technology. Specificallybut without limitation, the principles described may be used fordetermining concentrations of other materials in samples.

Thus the example embodiments and arrangements achieve improvedcapabilities, eliminate difficulties encountered in the use of priormethods and systems, and attain the desirable results described herein.

In the foregoing description, certain terms have been used for brevity,clarity and understanding. However, no unnecessary limitations are to beimplied therefrom because such terms are used for descriptive purposesand are intended to be broadly construed.

Moreover the descriptions and illustrations herein are by way ofexamples and the invention is not limited to the features shown anddescribed.

Further, it should be understood that features and/or relationshipsassociated with one embodiment can be combined with features and/orrelationships from other embodiments. That is, various features and/orrelationships from various embodiments can be combined in furtherembodiments. The inventive scope of the disclosure is not limited toonly the embodiments shown or described herein.

Having described the features, discoveries and principles of theexemplary embodiments, the manner in which they are constructed,operated, utilized and carried out, and the advantages and usefulresults attained, the new and useful arrangements, combinations,methodologies, structures, devices, elements, combinations, operations,processes and relationships are set forth in the appended claims.

We claim:
 1. Apparatus comprising: an analytical cell configured for usein conjunction with an atomic absorption spectrometer usable todetermine a mercury concentration in a sample material, wherein theanalytical cell includes a body, wherein the body generally bounds aninterior area, is elongated along a longitudinal direction and includesa first end and a second end opposed of the first end, a first windowadjacent the first end and a second window adjacent the second end,wherein the first and second windows are generally transparent toresonant radiation of mercury, wherein one of the first and secondwindows is configured to be optically connected with an atomicabsorption spectrometer, a gas sample inlet port on the body andlongitudinally intermediate of the first and second windows, wherein thegas sample inlet port is configured to deliver into the interior areaheated sample material vapor, a pair of gas outlet ports each of whichgas outlet ports is configured to enable gas to leave the interior area,wherein a first gas outlet port is positioned longitudinallyintermediate of the gas inlet port and the first window, and a secondgas outlet port is positioned longitudinally intermediate of the gasinlet port and the second window, a pair of clean gas inlet flow ports,wherein each gas inlet flow port is configured to deliver into theinterior area, sample material-free gas, wherein a first clean gas inletport is positioned to deliver sample material-free gas longitudinallyintermediate of the first window and the first gas outlet port, and asecond clean gas inlet port is positioned to deliver samplematerial-free gas longitudinally intermediate of the second gas outletport and the second window, wherein in operation of the analytical cell,the sample material-free gas flow reduces sample material reaching thefirst and second windows to maintain window transparency such thatheated sample material vapor within the analytical cell can be analyzedthrough operation of the atomic absorption spectrometer directingradiation through the first and second windows.
 2. The apparatusaccording to claim 1 wherein the analytical cell includes cell heaters.3. The apparatus according to claim 2 wherein the cell heaters areconfigured to maintain the interior area at 600-700° C.
 4. The apparatusaccording to claim 2 wherein the other of the first and second windowsis operatively connected with a retroreflector.
 5. The apparatusaccording to claim 4 and further comprising: a thermal atomizer, whereinthe thermal atomizer is in hermetic fluid sealed connection with the gassample inlet port.
 6. The apparatus according to claim 5 wherein thethermal atomizer heats sample material vapor to 600° to 950° C.
 7. Theapparatus according to claim 5 and further comprising: a sample inputunit, wherein the sample input unit is in hermetically sealed fluidconnection with the thermal atomizer, wherein the sample input unitincludes a nebulizer in operative connection with a supply of liquidsample material.
 8. The apparatus according to claim 5 and furthercomprising: a sample injecting pump, wherein the injecting pump is influid communication with the thermal atomizer.
 9. The apparatusaccording to claim 7 wherein the nebulizer includes a nozzle, andwherein the thermal atomizer includes an axial elongated interior area,wherein the nozzle is configured to deliver an aerosol spray of samplematerial coaxially aligned into the axial elongated interior area. 10.The apparatus according to claim 7 and further comprising: a mixer,wherein the mixer has three ports, wherein the nebulizer includes a gasport and wherein a first port of the mixer is in operative connectionwith the nebulizer gas port, wherein a second port of the mixer isfluidly connected to a distilled water supply, wherein a third port ofthe mixer is fluidly connected to a supply of carrier gas.
 11. Theapparatus according to claim 7 wherein the sample input unit contains aholder of the nebulizer, wherein a cavity extends between an interiorwall of the holder and the nebulizer, wherein the cavity is fluidlyconnected with an internal cavity of the thermal atomizer, and whereinthe cavity of the nebulizer is fluidly connected with a supply ofcarrier gas.
 12. The apparatus according to claim 7 and furthercomprising: a gas collector in operative connection with the first andsecond gas outlet ports, wherein the gas collector includes a cooler anda liquid gas separator.
 13. The apparatus according to claim 12 whereinthe gas collector further includes a liquid holding reservoir in fluidconnection with the liquid gas separator, and a return pump in fluidconnection with the liquid holding reservoir.
 14. The apparatusaccording to claim 13 wherein the clean gas inlet flow ports compriseopenings through which sample vapor free air is enabled to enter theinterior area.
 15. The apparatus according to claim 1 wherein each ofthe pair of clean gas inlet flow ports includes an opening through whichsample vapor free air is enabled to enter the interior area.
 16. Theapparatus according to claim 1 wherein the analytical cell isoperatively coupled through the first window with an atomic absorptionspectrometer and wherein the second window is optionally coupled with aretroreflector, wherein the retroreflector is positioned so thatradiation from the atomic absorption spectrometer passes through thefirst and second windows and is returned by the retroreflector throughthe second window and the first window back to the atomic absorptionspectrometer.